This invention relates to an anti-reflection device for a VDT (visual display terminal) which is attached to a CRT display frame.
FIGS. 1 and 2 show the construction of a conventional anti-reflection device for a VDT in plan and in section. The VDT anti-reflection device 15 shown in FIGS. 1 and 2 is used to limit reflection of incident light 11 from a light source (not shown). The amount of reflected light 12 reflecting from a glass screen surface 10 of a CRT (cathode ray tube) display is about 4.25% of the amount of incident light 11. Reflected light is the greatest cause of fatigue on a VDT operator's eyes, which is a considerable problem in offices. To minimize the amount of reflected light 12, a VDT anti-reflection device 15 is attached to a frame 9 of the CRT display screen 10. However, a certain amount of light 12a is also reflected from the surface of an anti-reflection film 6, and it is impossible to change the direction of this reflected light 12a since, as shown in FIGS. 1 and 2, the frame 14 in which the anti-reflection film 6 of the VDT anti-reflection device 15 is stretched is fixed to the frame 9 of the CRT display by adhesive tape 8. As shown in FIG. 2, the screen 10 of the CRT display is inclined at about 10.degree. so that it faces slightly upwards. The light 11a emitted by the light source (not shown) and reflected as light 12a by the anti-reflection film 6 therefore tends to travel toward the eye 13 of the VDT operator. Other anti-reflection techniques are known, including a multi-coating method in which a glass plate on which an anti-reflection film is formed by vapor deposition is attached to the screen surface of the CRT display with a transparent resin, a sand blast method in which irregularities are formed in the screen surface of the CRT display by blowing sand against the surface, and a direct etching method in which irregularities are formed by blowing hydrofluoric acid against the screen surface of the CRT display. All of these methods employ direct processing of the screen of the CRT display. Such surface processing reduces the transparency of the screen while failing to completely eliminate reflection.
The above-discribed conventional VDT anti-reflection device 15 has the additional problem that light 12a reflected from the anti-reflection film 6 is directly visible depending upon the disposition of the CRT display and the light source. Also, none of the multi-coating methods, sand blast methods or direct etching methods can change the direction of the reflected light 12 from the screen 10 of the CRT display.